| dc.description.abstract | Spray drying is one of the most commonly used methods of producing functional powders in industrial processes because of its advantages for low cost, simple process, large-scale industrial production and easy control of powder-molded structures. Due to the increasingly complex structure of functional powders, the analysis of spray-drying technology in the manufacture of functional powders has become an important issue for the development of the industry in recent years. The basis of the theoretical model of spray drying technology is based on a single droplet which undergoes the drying and precipitation processes. Droplet evaporation has two key processes: evaporation process and solidification precipitation process. This study proposes a mathematical model that considers both two mechanisms. The volume of fluid method (VOF) in ANSYS Fluent was used to capture the interface and simulate a drying process of a saline droplet in a static open space. To investigate the influence of ambient temperatures on the final structure of solid particles, simulations were performed with ambient temperature of 40℃、60℃ and 80℃, respectively.
Simulation results show that when the ambient temperature changes, due to the difference in the evaporation rate, the structure of the final salt particles is obviously different. When the ambient temperature is 40℃, the salt particles is a uniform solid structure. When the ambient temperature is 60℃ and 80℃, the salt particles are hollow structure. The higher the ambient temperature, the smaller the porosity of the outer salt shell formed, the bigger the porosity difference between the inner and outer salt shell, and the thinner of the shell thickness. Therefore, it can be speculated that there is a critical ambient temperature between 40℃ and 60℃ at which the structure of the salt particles will change from a solid particle to a hollow shell particle. Increasing the ambient temperature will result in a thin shell spherical salt particle. | en_US |